A Sim is a human being who functions as the player's character (or characters) in their game of The Sims FreePlay.
When you first start the game, the first life stage of a Sim you'll create is an Adult. Create A Sim (CAS for short) is where players change their Sim's hair, clothes, make-up, etc. It is free to use whenever during the game, however there is a 'Ultimate Makeover' option costing 12 Lifestyle Points. Using this option players can change their Sim's name, gender and skin colour.
In the Halloween 2017 Update, there is a new tab in the wardrobe called 'Body Paint'. Using this option can change your Sim's skin colour. They can only be unlocked during the Ghost Flustered quest.
See also: Needs.
See also: Hobbies
See also: Relationships.
See also: Life Stages.